Auxin Metabolism and Adventitious Root Initiation

Abstract

In this chapter I will report on and discuss the role of auxins in adventitious root initiation, particularly the relations between endogenous indole-3-acetic acid (IAA) and the early events of adventitious rooting. The fact that IAA is involved is well established, although much of the data to support this is circumstantial. It will be not possible in this review paper to describe all the work on auxin application, transport and metabolism that might be relevant to studies of adventitious root initiation. Evidence derived from studies on auxin application has been reviewed many times [e.g., Audus (1959) and Blakesley et al. (1991b)] and will not be considered in detail in this paper. Evidence from more recent work on the analysis of endogenous auxin, and from studies on transgenic plant tissue, will be germane to the present paper. From these studies it will be apparent that we still do not have a clear understanding of the exact role of auxin in the process of adventitious root initiation. The aim of the latter part of this paper will be to describe briefly the newer technologies which are available to plant developmental physiologists, and to indicate new directions for researchers to approach the problem of auxin involvement in adventitious root initiation.

Blakesley, D., Weston, G.D., and Elliott, M.C., 1991a, Endogenous levels of indole-3-acetic acid and abscisic acid during the rooting of Cotinus coggygria cuttings taken at different times of the year, Plant Growth Reg. 10:1.CrossRefGoogle Scholar

Gaspar, T., Penel, C., Castilllo, F.J., and Greppin, H., 1985, A two step control of basic and acidic peroxidases and its significance for growth and development, Physiol. Plant. 64:64.CrossRefGoogle Scholar